Gernot Hoffmann CIE Color Space

12.2 Matrices / 709 + D65 / sRGB
ITU-R BT.709 Primaries and white point D65 [9]. Valid for sRGB.
Data are in the Pascal source code.
Program CiCalc65;
{ Calculations RGB—CIE }
{ G.Hoffmann February 01, 2002 }
Uses Crt,Dos,Zgraph00;
Var r,g,b,x,y,z,u,v,w,d : Extended;
i,j,k,flag : Integer;
xr,yr,zr,xg,yg,zg,xb,yb,zb,xw,yw,zw : Extended;
prn,cie : Text;
Var Cxr,Crx: ANN;
Begin
ClrScr;
{ Rec 709 Primaries }
xr:=0.6400;
yr:=0.3300;
zr:=1-xr-yr;
xg:=0.3000;
yg:=0.6000;
zg:=1-xg-yg;
xb:=0.1500;
yb:=0.0600;
zb:=1-xb-yb;
{ D65 White Point }
xw:=0.3127;
yw:=0.3290;
zw:=1-xw-yw;
{ White Point Correction }
D:=(xr-xb)*(yg-yb)-(yr-yb)*(xg-xb);
U:=(xw-xb)*(yg-yb)-(yw-yb)*(xg-xb);
V:=(xr-xb)*(yw-yb)-(yr-yb)*(xw-xb);
u:=U/D;
v:=V/D;
w:=1-u-v;
{ Matrix Cxr }
Cxr[1,1]:=u*xr/yw; Cxr[1,2]:=v*xg/yw; Cxr[1,3]:=w*xb/yw;
Cxr[2,1]:=u*yr/yw; Cxr[2,2]:=v*yg/yw; Cxr[2,3]:=w*yb/yw;
Cxr[3,1]:=u*zr/yw; Cxr[3,2]:=v*zg/yw; Cxr[3,3]:=w*zb/yw;
{ Matrix Crx }
HoInvers (3,Cxr,Crx,D,flag);
Assign (prn,’C:\CiMalc65.txt’); ReWrite(prn);
Writeln (prn,’ Matrix Cxr’);
Writeln (prn,Cxr[1,1]:12:4, Cxr[1,2]:12:4, Cxr[1,3]:12:4);
Writeln (prn,Cxr[2,1]:12:4, Cxr[2,2]:12:4, Cxr[2,3]:12:4);
Writeln (prn,Cxr[3,1]:12:4, Cxr[3,2]:12:4, Cxr[3,3]:12:4);
Writeln (prn,’ Matrix Crx’);
Writeln (prn,Crx[1,1]:12:4, Crx[1,2]:12:4, Crx[1,3]:12:4);
Writeln (prn,Crx[2,1]:12:4, Crx[2,2]:12:4, Crx[2,3]:12:4);
Writeln (prn,Crx[3,1]:12:4, Crx[3,2]:12:4, Crx[3,3]:12:4);
Close(prn);
Readln;
End.
Matrix Cxr
X 0.4124 0.3576 0.1805
Y 0.2126 0.7152 0.0722
Z 0.0193 0.1192 0.9505
Matrix Crx
R 3.2410 -1.5374 -0.4986
G -0.9692 1.8760 0.0416
B 0.0556 -0.2040 1.0570
X = C xr R
R = C rx X
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